Renewable fuse



W. H. SCHRUPP RENEWABLE FUSE June 3, 1930.

Filed June 15, ,1927

Patented June 3, 1930 UNITED STATES WALTER H. SCHRUIPP, OF GRANITEFALLS, MINNESOTA RENEWABLE FUSE Application filed June 15,

The present invention relates to improvements in renewable fuses andmore particularly to that type of fuse commonly knownas tubular fusesand of that character as em ployed as a protector for telephone systems.

With the usual type of tubular fuse as now employed in connection withtelephone systems, the fusible element is soldered at both ends to themetallic ends of the fuse shell or barrel, and thus necessitates thatthe fuses be returned to a repair shop for the renewing of the fuse whenblown.

It is therefore a primary object of the present invention to provide animproved tubular fuse embodying features whereby a new fuse may bereadily inserted into the fuse shell and connected with the metallicends of the shell merely by employment of a wrench or a pair of pliersand thus allowing the fuse to be renewed at its mounting location in avery short time and without requiring that the fuse be transmitted to arepair shop in order that the terminals of the fusible element may beconnected with the metallic ends of the fuse.

A further object of the invention is to provide a renewable fuse of thetubular type embodying means whereby the fusible element may be readilyinserted through the tubular shell of the fuse and be coupled as bymeans of suitable nuts to the metallic ends of the fuse.

A further object of the invention is to provide a renewable fuse havingmetallic heads so constructed and associated with the tubular shell ofthe fuse as to permit of the fusible element to be readily associatedwith the fuse without requiring removal of the heads for properpositioningof the fusible elementlon gitudinally within the tubularshell.

A. still further object of the invention is to provide a renewable fuseof the tubular type which may be very economically manufactured and onewherein fragmentary portions of the blown fuse element may be readilyremoved from the tubular shell prior to insertion of the new fuse.

Other objects and advantages of the invention will be apparent duringthe course of the following detailed description taken in connectionwith the accompanying drawing 1927. Serial No. 199,047.

forming a part of this specification and in which drawing:

Figure 1 is a side elevation of the improved renewable fuse.

Figure 2 is a view showing the various elements constituting the fuseand showing the shell and heads of the fuse assembled and inlongitudinal section.

Figure 3 is a central longitudinal section through the fuse and showingthe fuse wire in position. i

Figure at is a plan view of the upper end of the fuse as illustrated inFigure 2.

Figure 5 is an end view of the lower end of the fuse as illustrated inFigure 2.

In the drawing, and wherein similar reference characters designatecorresponding parts throughout the several views, the improved fusehasbeen shown as embodying a tubular main body portion or shell 10 which isformed of a suitable insulating material such as fiber or the like, andwith the bore of the shell being of equal diameter throughout the lengthof the shell.

The insulating shell or main body portion 3 10 is provided with upperand lower metallic ends or heads 11 and 12 respectively, and which headsserve as coupling means for the terminal portions of the fuse wire 13which is adapted to extend through the tubular shell 10.

The metallic head 11 and which is intended to be connected with theupper end of the shell 10 embodies a plug portion 14: of a diameter tobe snugly inserted into the upper end of the shell, and the outer end ofthe plug portion is provided with an annular fiange or shoulder 15 fromwhich extends in axial alignment with the portion 14, an externallyscrew'threaded extension or stem portion 16 of a diameter less than thatof the flange 15.

Thus it willbe seen; that the annular flange 15 forms an annularoutwardly facing seat 17 at the inner or lower end, of the screwthread-- ed extension 16. As will be observed in Figures 2 and 3, theflange 15 abuts with the upper end of the shell 10 and thus limitsinward movement of the head. The head 11 is provided with an axiallyextending bore 18 which as will be observed extends axially- Gil Til

through the plug portion M and extension 16, and this bore is flaredinto a bell shaped mouth 19 at the inner end of the head with the wallof the mouth terminating in the circumference of the plug portion 14; sothat no shoulder or abutment is formed at the inner end of the plugportion such as would prevent ready upward movement of the fuse wirethrough the bore of the head. The head 11 may be secured in the shell 10in any preferred manner and in the example shown diametrically arrangedpins 20 e? through the shell and plug portion for retention of the headin coupled relation to the shell. The externally threaded extension orstem 16 provided with a longiteulinally ex:- tending slot 21 whichextends to. oughout the length of the stem and opens into the he. 18 isclearly illustrated in Figures 823 l. It will he observed that the hereit; is relatively large diameter and it may here he well lo state thatthe object in so having the bore 18 as large as possible without weaening the stem 16 to an undesirable (h will allow for a relatively largeopenin' ing formed into the here of the tubular 10 for allowing anyfragn'ientary portion a blown fuse wire to he removed through bore 18.

Referring now to the metallic end or head 12 for connection with theopposite or lower end of the shell 10, the same inclurrs a plug portion22 which is readily insertihle into the bore of the shell and isprovided at its outer end with an annular flange or shoulder forming anoutwardly facing seat 24- and projecting from the seat 2l in axialalignment with the plug 22 a threaded shank 25. The head 12 may beretained in coupled relation to the shell 10 as by means of suitablediametrically arranged pins 26 which pass through the shell 10 and intothe plug portion. 22. The inner end of the plug 22 is provided with aflaring pocket 27 prowld with a rounded bottom 28. will he so thisflaring pocket 27 merges at its mouth p tion into the circumference ofthe plug portion 22, and is of a depth substantially half the length ofthe plug portion. Extend ng (JILL in angular relation to thcoaxis of thehead '12 from the rounded bottom 28 of the pool to the seat face 24 toone side of the eircrunference of the shank 25, is a passageway 29forming commui'iication between the hero of the shell and the head seat24.

A washer 3O slidably fits over the threaded extension 16 and nuts 31 and32 are threaded along the extension over the washer 30, wnile a washer33 is intended to be slidable over the shank 25 and followed by aclamping nut 34.

lVhen desiring to renew the used wire, the nuts, together with thewashers are ii-stremoved from the heads 11 and 12 and one end of thefuse Wire 13 is inserted through the seat 24 in a manner passageway 29and will be guided tlnrough the bore 18 of the head ll. by the flaringmouth 19 until the terminal. portion which has been inserted through theshell projects for a slight distance past the outer end. of the threadedextension ill and the opposite terminal of the wire extends past theoutwardly facing seat of the head 12. The projecting lower end of thewire may then be wound about the shank adjacent the illustrated in Fiures .1 and Z-land then the washer 23 and nut all positioned on theshank so that tightening of the nut will .lirmly clamp the lower )1 trminal of the fuse wire between the .rasher and seat The upperprojecting terminal of the fuse wire is then drawn through the slot 21and. wrapped about the base portion of the threaded extension 16 uponthe seat 1'? and after which the washer All) and nut 31 may he appliedto the extension for firmly clamping the to dual of the fuse *irebetween-the washer 39 and flange 15. Thus it will be seen that theterminals of the fuse wire are ehectively connected with the metallicheaus at the opposite ends of the insulating shell 10 without thenecessity of soldcring the terminals of the wire to the heads, and thatno strain imparted to that portion of the fuse wire ex: nding throughthe shell during clamping of the terminal portions of the fuse wire tothe metallic ends.

It will further be noted that the improved manner of connecting theterminal portions of the fuse wire to the terminal portions of the fusebody does not increase the external diameter of the tubular shell andthus allows for the fuse to he used at locations and installed in amanner as are the tubular fuses new in neral use in connection withtelephone systems.

newahle features whereoy'the fusible element is effectively connected atits end to the termi- Froni "-e foregoing d 'ipliion it will he apparentthat an improved and novel and rehas been provided embodying nalportions of the fuse body without the re quiring of soldering or specialtools for renewing of the elements, and embodying features wherchy thefusible elen'lent is readily insertihle into the carrier body therefor,and one wherein the fragmentary portions of the blown fuse may he easilyremoved prior to application of the new fuse.

Various changes may be made to the specific form of the invention hereinshown and described, .vithout departing from the spirit of the inventionor the scope of the following claims.

I claim 1. In a renewable fuse, a tubular shell, a fusewire and aterminal connector for the fuse wire comprisiu a tubular u'letallic bodyproviding a longitudinal passageway and having an externalannular flangeformed intermediate its ends providing a plug portion for slidablyfitting into the bore of the tubular shell and an externally threadedextension slotted thruout its length, said passageway thru the tubularmetallic body having a bell shaped mouth at its inner end flaring intothe circumferential surface of the plug portion, and retaining meansthreaded upon the extension for clamping the terminal portion of thefuse wire in engagement with the outer face of the annular flange.

2. In a renewable fuse, a tubular shell, a fuse wire, and a terminalconnector for the fuse Wire comprising a metallic head including a plugportion for insertion into the bore of the tubular shell and anexternally threaded shank portion arranged co-axially of the plugportion and having an annular flange formed at its inner end andproviding an outwardly facing annular seat, said plug portion having aflaring pocket opening at its inner end and provided with a roundedbottom, and having a small passageway extending from the base of therounded bottom in angular relation to the axis of the plug portion andopening upon the annular seat at one side of the threaded shank portion,and means threaded upon the shank portion for clamping the terminalportion of the fuse Wire extending thru thetubular shell in engagementwith the outwardly facing seat.

3. A renewablefuse comprising a tubular holder of insulating material, ametallic head for the upper end of the holder having an external annularflange providing an outwardly facingannular seat, said head having arelative y large opening axially therethru provided with a flaring innerend, a metallic head for thelower end of the holder having an externalannular flange providing an outwardly facing annular seat, said headhaving a flaring pocket opening at its inner end and provided with arounded bottom and having a diagonal passageway extending from the baseof the rounded bottom and opening at the annular seat, a fuse wireinsertable thru the tubular body thru the head at either end thereof,and means for clamping the terminal portions of the fuse wire inengagement with the outwardly facing head of the head.

WALTER H. SCHRUPP.

